m ⁶ A deposition is regulated by PRMT1‐mediated arginine methylation of METTL14 in its disordered C‐terminal region

Abstract

The N6‐methyladenosine (m6A) RNA modification serves crucial functions in RNA metabolism; however, the molecular mechanisms underlying the regulation of m6A are not well understood. Here, we establish arginine methylation of METTL14, a component of the m6A methyltransferase complex, as a novel pathway that controls m6A deposition in mammalian cells. Specifically, protein arginine methyltransferase 1 (PRMT1) interacts with, and methylates the intrinsically disordered C terminus of METTL14, which promotes its interaction with RNA substrates, enhances its RNA methylation activity, and is crucial for its interaction with RNA polymerase II (RNAPII). Mouse embryonic stem cells (mESCs) expressing arginine methylation‐deficient METTL14 exhibit significantly reduced global m6A levels. Transcriptome‐wide m6A analysis identified 1,701 METTL14 arginine methylation‐dependent m6A sites located in 1,290 genes involved in various cellular processes, including stem cell maintenance and DNA repair. These arginine methylation‐dependent m6A sites are associated with enhanced translation of genes essential for the repair of DNA interstrand crosslinks; thus, METTL14 arginine methylation‐deficient mESCs are hypersensitive to DNA crosslinking agents. Collectively, these findings reveal important aspects of m6A regulation and new functions of arginine methylation in RNA metabolism.

Recognition of G-quadruplex RNA by a crucial RNA methyltransferase component, METTL14

“…Deletion of the RGG domain of METTL14 resulted in a more than 10-fold decrease in RNA binding affinity for G4-RNA1 ( K D = 419 ± 109 nM) compared to MTD3/MTD14-RGG ( Supplementary Figure S3C ). The result is in good agreement with previous reports showing that the RGG domain of METTL14 contributes remarkably to the RNA binding of METTL3/METTL14 ( 14 , 16 ). These results showed that MTD3/MTD14-RGG specifically recognizes G4-forming RNAs and the RGG domain is responsible for the strong RNA binding of METTL3/METTL14.…”

“…METTL14 also contains RGG repeats at the C-terminus. The RNA binding ability of METTL14 was considerably decreased in the deletion mutant of the METTL14 RGG domain, thus indicating that METTL14 RGG repeats are important for RNA binding ( 14 , 16 ). However, the RNA binding specificity of METTL14, especially toward rG4 sequences, is elusive.…”

RNA m6A Modification in Immunocytes and DNA Repair: The Biological Functions and Prospects in Clinical Application

“…It proved to be an initial signal of interaction between METTL14 and RNA polymerase II, which will afterwards implement the m 6 A modification of target mRNA. Subsequent studies have confirmed that METTL14 arginine methylation is associated with the enhanced translation of DNA repair genes (Wang Z et al, 2021). Recent studies even clarified the correlation between DNA damage repair and m 6 A-modified retrotransposable element (RTE) RNAs, in which intronic Long Interspersed Element-1 (LINE-1) interacts with the hosting gene transcription, resulting in the downregulation of its expression (Xiong et al, 2021).…”

N6-methyladenosine-dependent signalling in cancer progression and insights into cancer therapies

“…Although METT L14 has no catalytic activity, it can form a stable complex with METTL3 to recognize the substrate RNAs [17]. In addition, the arginine methylation of METTL14 affects the binding of METTL14 to RNA substrates and the interaction with RNA polymerase II [18]. Moreover, when the ubiquitination process of METL14 is inhibited, it contributes to the stability of METL14 and its methylation of target RNA [19].…”